04 acoustical strategies acoustical consultants While architects have general knowledge about many concepts in design, acoustical consultants, or acousticians are specialists in sound in the built environment. The most effective and comfortable spaces are made when architects and acousticians team up and acoustical goals are set and acted upon early in the design process. Here are some questions from architects and some answers from an acoustician1: When should I consult an acoustician? Most projects can use at least some input from a consultant, whether it’s a quick phone call or a scheduled appointment. Definitely call an acoustician early in the process of designing spaces (e.g., lobby, house of worship, concert hall) that have specific room acoustic requirements like reverb or sustained sound control. What can I do to prepare for a discussion with an acoustician? It is most useful for the architect to have a clear vision of what the space should be, how it will be used, and how it should feel when occupied. It is ideal if the architect has basic knowledge of acoustical principles but is open to the expertise of the acoustician. Further, an architect can achieve the best results when they connect the acoustician directly to the end user of the space, even in the form of a questionnaire. How much should absorptive material should I add? How much deadening is too much? The amount of necessary acoustical intervention can be complicated, and this is an appropriate task for the consultant. You can get a general idea from the volume of the room, the surfaces in the room, and the target reverberation time. In the end, the answer to the question depends on what the room is to be used for. The sound of the room should match its purpose and the expected sound quality. For example, a very dry lobby space would not feel right.
General acoustic strategies In order to create effective acoustic environments, designers should consider how the materials and structures in a room (and between rooms) respond to and affect sound. In general, the following three strategies can be used to manipulate sound in a space:
A B C
Absorb reverberating sound energy to create comfortable room acoustics. Block isolated sounds from transmitting to adjacent spaces. Cover to mask distracting background noise.
How sound behaves A wavefront of sound will behave differently depending on the surface it hits. Some materials are effective barriers to sound, while others are effective absorbers. Some materials are both barriers and absorbers, and others are neither. Consider a material’s STC, NRC, and texture to get an initial idea of how it will perform.
Transmission
Specular Reflection
Diffuse reflection
Absorption
Sound penetrates through
Sound bounces off smooth,
Sound is scattered by faceted,
Sound energy is trapped
and continues past a surface.
hard surfaces at the same
rough, or generally irregular
in soft, porous surfaces.
angle from which it came.
surfaces.